This invention relates to a key actuating device of an automatic playing keyboard instrument such as an automatic player piano and, more particularly, to a key actuating device of such instrument capable of improving the accuracy of a key depression and release control and reducing noise occurring in actuation of keys of the automatic keyboard instrument.
In an automatic playing keyboard instrument such as an automatic player piano is incorporated a key actuating device for making an automatic performance on the basis of prerecorded performance information or performance information supplied from outside.
FIG. 20 shows an example of a prior art key actuating device incorporated in an automatic player piano. In the figure, an automatic player piano 71 has a keyboard including white keys 73 and black keys 74, a string striking mechanism 77 transmitting the movement of each key 73 or 74 to a hammer 75, a string 79 struck by the hammer 75 and a damper 78 for restraining vibration of the string 79.
A key bed 84 is provided under the white keys 73 and the black keys 74. A balance rail 80 and a front rail 82 are fixedly provided on the upper surface of the key bed 84. The keys 73 and 74 are rockably supported on a balance pin 81 provided on the upper surface of the balance rail 80. An oval key pin 85 fixed on the lower surface of a front end portion of the key 73 or 74 projects downwardly from the lower surface of the key 73 or 74 toward the front rail 82 and is engaged in a depression 82a formed in the upper portion of the front rail 82. An undesired transverse movement of the keys 73 and 74 can be prevented by this arrangement. A push-type solenoid 83 is provided on the upper surface of the key bed 84 rearwardly of the balance rail 80 in the longitudinal direction of the key 73 or 74 and beneath the key 73 or 74. Upon actuation of the solenoid 83, a plunger 83a of the solenoid 83 projects upwardly and pushes up the key 73 or 74 in a portion below a wippen 86 thereby to pivot the key 73 or 74 downwardly about the balance pin 81. This movement of the key is transmitted to the hammer 75 and the damper 78 through the string striking mechanism 77. The damper 78 thereby is released from the string 79 and the hammer 75 simultaneously is pivoted counterclockwise as viewed in the figure to strike the string 79. This action is continuously made in response to output signals from a control unit 90 and an automatic performance thereby is performed.
A key holding member 87 is provided for holding the key 73 or 74 at a position above the balance pin 81 against an upward movement of the key 73 or 74 when the middle portion of the key 73 or 74 is subjected to an upwardly acting force excerted by the solonoid 83.
The prior art key actuating device of an automatic playing keyboard instrument has the following disadvantages:
1. Noise is generated when the plunger 83a moves in a sliding movement by actuation of the solenoid 83, when the foremost end portion of the plunger 83a abuts against the lower surface of the key 73 or 74, and when the plunger 83a returns to its final sliding stroke position. PA1 2. The sliding movement of the plunger 83a and the abutment of the plunger 83a against the lower surface of the key 73 or 74 tend to cause damage or wear of the plunger 83a itself and the lower surface of the key 73 or 74 with resulting loss or reduction in reliability and durability of the key actuating device. PA1 3. Since the key 73 or 74 is actuated by pushing it in the portion below the wippen 86, the point at which the key actuating force is applied differs from the case where a pianist plays the piano and this makes it difficult to reproduce a sound with a high fidelity. PA1 4. It is difficult to reproduce a fine performance technique depending upon the pianist's hands by a so-called impact actuation system according to which the foremost end portion of the plunger 83a is caused to abut against the lower surface of the key 73 or 74. It is therefore impossible by the prior art device to reproduce a half-key technique in which a lower half portion of a key is used with a stroke of less than about 5 mm, or to reproduce a performance by rapid, repeated striking of the same key. PA1 5. It is difficult in the impact actuation system to perform a feedback control by introducing, for example, a servo system and, therefore, improvement of the accuracy of control is limited. PA1 6. If the position of the key holding member 87 which is required for holding the key 73 or 74 against an upward movement caused by pushing by the plunger 83a is not properly determined, the rocking movement of the key 73 or 74 will not be made in a desired manner with resulting deterioration in the quality of a sound produced.
It is, therefore, an object of the invention to provide a key actuating device of an automatic playing keyboard instrument which has eliminated the above described disadvantages of the prior art key actuating device.